


Changing of the Guard

by SoloShikigami



Category: Undertale (Video Game)
Genre: Alternate Universe - Twins, Alternate Universe - Underfell, BDSM elements, M/M, Sibling Incest, Underfell Papyrus, Underfell Sans, Underfell W. D. Gaster
Language: English
Status: Completed
Published: 2018-07-04
Updated: 2018-11-01
Packaged: 2019-06-05 06:34:15
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 9,120
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15164759
Author URL: https://archiveofourown.org/users/SoloShikigami/pseuds/SoloShikigami
Summary: Sans was Gaster’s guinea pig, but now the Royal Scientist needs a new subject. Sans won’t back down easily, as Gaster sets his sights on the twins.





	1. Chapter 1

**Author's Note:**

  * For [KonekoKittyCat](https://archiveofourown.org/gifts?recipient=KonekoKittyCat).



> Wow, been a while since I posted a new piece of work. Just as a heads up, there will be fontcest later, not sure how far exactly it will go, will update tags more as we go along, so in the meantime, sit back and enjoy!
> 
> And if you like what I do, come visit me on[Tumblr! (18+ only please)](https://soloshikigami.tumblr.com/)

          Life had never seemed to deal Sans a good hand. He would say that he was lucky to never have been a card player, because he would have folded a long time ago.

          But of course, his brothers would groan at the pun. So worth it.

          Gaster had great expectations of his eldest son to follow in his footsteps in science, or at least, be the smartest assistant second only to Gaster himself, and a good slave. He also wanted a second son to act as his own personal bodyguard.

          Sans lost hope in karma when Papyrus turned out to be twins.

          Gaster continued to call them both Papyrus, as whatever order would be given to one would naturally go to the other, and to cut down on their sense of self-identity.

          Sans decided to give each of them a nickname, Edge and Fell, knowing that treating two monsters as one could be devastating to their psyche. The names were used in secret, and they seemed to revel in this shared secret with their older brother.

          As Gaster descended into madness, Sans had to put himself between his father and his brothers, convincing Gaster to use him as a guinea pig for his experiments instead of the younger monsters.

          Of course, that only lasted for so long, until Sans’ HP dwindled down from a healthy 20 to a feeble one.

          “You’ve been a good lab rat,” Gaster said one day as he was finishing up his calculations for The Core. “But your usefulness in that role has passed. You are too weak to endure even the simplest stages of my experiments.”

          “I can take it!” Sans insisted angrily, pounding his fist on a table. “Don’t touch the twins, they don’t deserve it.”

          “And you do?” Gaster chuckled. “How noble, Sans. What an odd trait for a child of mine to have. You certainly did not inherit it from me.”

          He walked out of the lab and towards the core, not caring much that Sans followed.

          “What the hell is that supposed to mean?” Sans demanded.

          “It means that I have failed to impart on you the traits of the truly brilliant. You cannot make strides and sacrifice yourself, at least not forever.”

          “I beg to differ,” Sans growled.

          “I have better things to do than to engage in an arbitrary argument that I know that I will win,” Gaster said, brushing past a pair of guards who were a pair of earlier victims to Gaster’s experiments on monster psychology; they no longer knew what their given names were, reduced to nearly mindless drones known only and RG01 and RG02.

          Sans paused to look up at the intimidating guards, tall and dressed head to toe in heavy black armor. He briefly saw the twins in their position in his mind’s eye, making him shudder as he brushed past to catch up to the Royal Scientist.

          “I must admit that you confuse me, Sans,” Gaster said with a sigh as continued to swiftly walk down the hall. “You have insisted on being the subject of my experiments simply for the sake of keeping Papyrus safe. However, this does beg the question, what is to stop me if you happen to dust as a result? Who will protect Papyrus then?”

          Sans growled, he knew Gaster was right, but it still pissed him off.

          “Maybe you shouldn’t dust your subjects, then, and… what the hell are they doing here?!”

          The corridor to The Core was always heavily guarded, hence the guards at the beginning of the hall, and there were also two guards for the doorway to the center of The Core itself. They tended to always be featureless guards decked in black armor, but this pair of guard were not featureless, not unknown.

          They were his brothers.

          “Greetings, Father,” the twins murmured in unison.

          “Papyrus,” Gaster said, giving them a nod as he pushed through the double doors.

          Sans stared at Gaster’s backside blankly before looking up at each of his brothers.

          “What are you two doing?” Sans mouthed just before he also pushed through the doors.

          Gaster stood at the controls to The Core, looking through his papers and making adjustments.

          “What are they doing there?” Sans demanded.

          “I really do not have time for this, Sans,” Gaster said with a sigh. “I’m on the verge of making The Core, and therefore us, more powerful than ever before and you are going to put it all on hold for some sentimentality?”

          “You know what? I am!”

          He stomped a foot down, and the whispers of battle music could be heard in the air. Gaster sighed, putting in a few more numbers before turning to face Sans.

          “Do you really think this is wise, son?” Gaster asked.

          “You have no right to call me your son, nor do you have any claim on the twins!”

          “Oh? And you do?”

          “Why not? I wouldn’t treat them the way you treated me! They’re monsters, not pets, not playthings, not fucking _test subjects_.”

          “Oh, my, this is interesting,” Gaster chuckled. “Have you developed feelings for your brothers, then? Because that’s what it sounds like.”

          Sans’ fingers twitching, partially in nervousness, and partially itching to hit Gaster with all the power he could muster.

          “I suppose there is little helping it, you’ve always been a little too attached to Papyrus, so I suppose this outcome was as likely as any other. What will it be now, Sans, how far are you willing to go for Papyrus?”

          Sans hesitated; he knew he cared very deeply for his brothers, but, how deep? This was the last thing he thought he would be questioning himself on today, much less have it brought up by Gaster. Was it all a trick, though? Gaster never did or questioned anything without having ulterior motives.

          Sans decided it didn’t matter. Opening his stance, he began gathering his magic, the energy swirling around him, making his lab coat flutter dramatically.

          “So you’re willing to go as far as to attack your own father,” Gaster murmured, setting his papers aside. “Very well, then.”

          Gaster began to invoke his own magic, his many hands, usually used to aid him in his work, flickered into existence around him, glowing with his dark purple magic, and all aimed at Sans.

          “Heh, you forget, Gaster, I may not have as much HP as I used to, but thanks to your experiments, I have powers that you have no chance against,” Sans said.

          “Mmm, perhaps, Sans, you do have a greater magic potential than I as well as tactics that I do not possess. You are quite the talent on the battlefield to be sure, but the question is, can you survive an unfair fight?”

          “Unfair? For me? You really have lost your mind.”

          “No, not for me. Three on one hardly seems fair to me.”

          “Three on one?”

          Sans started when hands landed firmly on his shoulders. A glance to one side showed Edge looking down at him with an unreadable expression. A glance to the other side showed the same from Fell.

          “You forget, Sans,” Gaster purred. “I have two very loyal bodyguards.”


	2. Chapter 2

**Summary for the Chapter:**

> Sans vs. Gaster - who will come out on top?

          Sans tensed under the hands of his brothers. They weren’t even supposed to be this close to The Core, but, perhaps now they were, if Gaster really had convinced them to be completely loyal.

          “So, do you really want to do this three on one?” Gaster asked, chuckling, teasing as he made his many hands move threateningly in unison.

          “I will do what I have to,” Sans growled.

          “Father, if I may?” Edge spoke up.

          Gaster blinked, looking a little surprised. “What is it?”

          “Perhaps this would be a good opportunity to test the true power of The Core, don’t you think?” Edge continued. “After all, if I recall correctly, many of The Core’s functions are based off of experiments you ran with Sans.”

          “My, my, Papyrus, I didn’t think you were listening,” Gaster said, sounding a touch pleased. “Perhaps you have some brains in you yet. While that is an intriguing notion, I’d prefer it if you both just dusted him so I can move on.”

          “I, too, would prefer to move on,” Fell said, voicing his impatience.

          “I think you both are being rash and missing out on a golden opportunity to see the cultivation of your experiments again the machine they created. But perhaps, Father, if it’s too much for you to handle, then, I suppose the LV should go to us,” Edge said.

          Sans’ soul stuttered as both grips tightened; was he going to be able to fight them both off on his own?

          But a growl from Gaster stayed their hands.

          “How dare you question me, and how dare you take what is rightfully mine,” Gaster snarled. “All right, let us see what Sans has to offer. I may not need to draw power from The Core for this weakling. Papyrus, move away.”

          The twins did as they were told, releasing their brother and stepping back.

          “Heh, bad move, pal,” Sans chuckled.

          Releasing the energy he gathered, he summoned his Blaster, the sharp-toothed skull hovering menacingly above him. It was taking a lot of energy, but he grinned at Gaster, his left eye glowing bright, magic smoking from the socket.

          “You ready to have a bad time?” Red asked.

          “Only if you are,” Gaster said with a smirk.

          The hands spun around Gaster and two blasters of his own appeared over his shoulders. They were sleeker, more streamlined and sophisticated than Sans’, glowing with Gaster’s purple magic.

          The two blasters’ mouths opened, gathering magical energy. Sans quickly got his blaster to do the same, all three blasters firing at just about the same time. The pressure of the attack caused Sans to slide back, planting a foot behind him to keep his balance and stance. Gaster didn’t move whatsoever.

          Sans concentrated more energy to the attack, pushing the purple beam of magic back with his red one, but slowly.

          Suddenly the purple beam disappeared, making Sans falter, and then forced to roll out of the way when short beams of magic began firing at him.

          Sans shot out his hand, trying to grip onto Gaster’s soul to at least make him stutter in his own attack, but it did nothing. Sans dodged another blast, trying to focus on making his blaster take at least one of the others out as he continued to dodge the blasts.

          “Come now, Sans, you can’t dodge forever!” Gaster cackled.

          “Try me!” Sans countered, jumping away from another attack.

          While Sans couldn’t concentrate enough to get his blaster to fire where he wanted it, he was doing a marvelous job dodging.

          “You’re slowing, Sans,” Gaster teased.

          “Fuck you!” Sans spat.

          Finally, his blaster got a shot off, grazing across Gaster’s leg. The other monster cried out in pain, one of his blasters flickering. It was more than enough to allow Sans to plant himself again in his original position and focus his blaster again. It shot the other blaster straight on and it dissolved.

          “No,” Gaster growled. “You little fuck.”

          The next blast was a surprise, as it came from one of the hands. Sans went to dodge again, but he was too late, and the attack grazed the side of his skull.

          Fell gasped and stepped forward, but Edge grabbed his shoulder.

          “Don’t move, brother,” he warned.

          Gaster chuckled, watching Sans struggle to get to his feet. There was a crack above one eye and his lab coat was ruffled, but he still looked as determined as ever.

          “Why are you so damn persistent?” Gaster sighed.

          “If you think I’m gonna give up so easily, you got another thing coming,” Sans murmured.

          “I see.”

          Sans reached out again to try to grab Gaster’s soul.

          “Haven’t we been through this, Sans? You are simply exercising the concept of insanity.”

          “And you’re terrible at paying attention!”

          Sans had controlled his blaster to appear behind Gaster and blasted away his remaining weapon. Gaster gasped, feeling the loss in his magic, and that was all Sans felt he needed and he rushed at the taller monster, shoving him back into the control panel.

          The computer overloaded immediately; not only was Sans charged with his own magic to be sure he had the ability to at least attempt to deal Gaster the final blow, but Gaster’s magic hands were also pressed back with their master.

          Sans grunted as he struggled to keep pressing Gaster into the machine, trying it ignore the rampant magic tearing through his body and the electricity singing through his bones. He let out a scream of rage to hide the pain, not noticing that something weighed on his soul, causing him to be pressed into the ground.

          _No, no, no,_ Sans thought as his vision faded. _Edge, Fell, I’m sorry._

          His last conscious thought was the hope that he at least gave the twins a way out.

 

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

 

          “Sans!” Edge cried, rushing forward as Fell continued using his blue attack to try to get his brother away from their father.

          Edge knelt and pulled Sans into his arms, checking him over.

          Fell let his attack go and joined his brother.

          “Is he okay?” Fell asked.

          “Not sure,” Edge murmured.

          Their attention was suddenly caught by an unholy scream. The twins looked up in horror to see that their father, the brilliant Royal Scientist, was melting. The black suit dripped from his body, his skeletal-like structure was also melting. His face contorted into a nightmarish expression.

          “Yoouuuu,” he growled in a voice that matched his grotesque form. “Killlll yyyooouuuu allll.”

          He slid off the panel and gathered his energy into a ball and pressed it towards the three.

          “Shit,” Edge swore.

          Fell immediately got to his feet and created a forcefield to shield them. The energy pressed against it. Fell had to readjust his stance, but he knew it wasn’t enough.

          “Gonna need some help!” he grunted.

          Edge carefully lay Sans down and joined his brother. The two still struggled and could feel the energy forcing them back as Gaster cackled.

          “Trrraaaaiiitorssss,” Gaster groaned. “Kiiiilllll!!!”

          “Edge, we can’t keep this up,” Fell said. “We have to retaliate.”

          “How?” Edge growled.

          “Quick burst, he won’t expect it, and we can push this back and use his own power against him.”

          “Sounds stupid,” Edge glanced over his shoulder at Sans, still unconscious. “Let’s do it.”

          Fell smirked, Edge met it and matched it and the two gathered their energy to put their plan into motion. They felt each other’s magic, they both synced to one another, and they didn’t even need to speak to one another to know when to make their move.

          It caught Gaster off guard, causing the melting creature to stumble back, flailing, then finally falling over the edge of the walkway and into the roiling lava down below with a horrible scream.

          The twins didn’t expect there to be a magical kickback, which blasted the two of them and Sans back, making them slide across the floor. The twins now had mirroring cracks of their own, but there was a much more important matter at hand.

          “We did it,” Fell murmured, slowly sitting up.

          “Yeah,” Edge said. “We, we did.”

          They stared at the spot where their father fell, his screams still echoing in their minds.

          “We can’t forget what he did, brother,” Edge murmured, wincing a little as he turned towards their senseless brother. “What he did to us, or what he did to Sans.”

          “Of course,” Fell said, also moving gingerly as he turned his attention to Sans.

          The twins carefully cradled Sans in their arms between them, taking in the moment, before there were shuffling steps and a scrape of a door being opened ever so slightly.

          “It’s over, Dr. Alphys,” Edge called out.

          “A-a-are you su-sure?” the yellow lizard monster stammered, poking her head in more.

          “Yes,” Fell said with a small sigh of impatience.

          Dr. Alphys shuffled in fully and approached them.

          “O-oh my, Sans,” she said, wringing her hands. “I-is he al-al-alright?”

          “Under our care, he will be,” Edge said, taking Sans into his arms completely and getting to his feet, Fell staying close to make sure he was steady.

          “We are clear on our arrangement?” Fell asked, turning to Dr. Alphys.

          “Of course,” the scientist replied, her voice steadying for once as she reached into her pocket. “There was a terrible accident; no one knows for certain what happened to Dr. Gaster, and he had sent his sons away the day before.”

          Dr. Alphys pulled out a small cube that glowed with varying colors and she pressed it into Fell’s waiting hand.

          “This was made after I studied Sans’ teleporting abilities. It should work without a problem, and it should take you three to the house in Snowdin,” Dr. Alphys explained. “Stand close, press the button on the side, and just hold on.”

          “Thank you, Dr Alphys,” Fell said, giving the nervous scientist a small smile. “It really is appreciated.”

          “Good luck, Doctor,” Edge added.

          Dr. Alphys gave them both a nod, a small, nervous smile, and she backed up as Fell looked for the little black button on the side of the box. He moved closer to his brothers, reaching over to grab Sans’ hand, pressed the button, and the three skeletons were gone.


	3. Chapter 3

**Summary for the Chapter:**

> Time to start putting the pieces of their broken lives back together.

            Edge and Fell had gathered long ago that something was going on behind their backs, and neither appreciated the secrecy. There was only so many times that Sans could have simple accidents like falling down stairs, walking into walls, or telling the wrong joke to the wrong monster (even though they were horrible enough to render him a beating). Considering Sans had given them their basic training, it was hard to believe that Sans was that clumsy.

            While their father’s true intentions to mentally enslave them were mainly thwarted by Sans giving them each their own names and treating them as individuals, the two used this very much to their advantage to confuse other monsters and fool their own creator. They were able to access some of the files Gaster had on them as well as the experiments that he had been running on Sans.

            Anger and hatred towards Gaster for what he had done started the twins on a path towards planning his destruction. However, on the other side of the coin, love for Sans and the love he showed them was what kept them motivated.

            It had taken some time for Edge and Fell to sort out their feelings for Sans, making sure that their love for him wasn’t due to simple brotherly bonds or an overclocked sense of duty towards him for what he had done for them. As they grew older and the more-than-brotherly feelings began taking over more and more, not only could the twins no longer deny their attraction, but also, they no longer wanted to. They loved Sans, and they loved each other, and they were going to find a way out of the prison they found themselves in.

            Fell groaned, slowly opening his eyes. He hand was still loosely wrapped around Sans’ hand, his other warmed by the broken and burned-looking box in his hand.

            “Mmph, where are we? Did it work?” Edge murmured, not moving from being curled protectively around Sans.

            “Yes, brother, it worked,” Fell said, wincing as he moved into a kneeling position. “There is no going back, now.”

            Edge grunted as he moved into a sitting position, his legs crossed, still cradling Sans, who only let out a small moan as he was moved.

            The two looked around the dark room; it was the living room of the house they had scouted out in Snowdin - it was abandoned and there didn’t seem to be any records of owners. Small slivers of light peeked through the boards that shuttered the windows. More boards blocked the door. Edge and Fell figured they could take the house as they pleased and no one would question it.

            “We have our work here cut out for us,” Fell said with a grimace as he ran a finger across the musty green and purple rug. “Do you think Sans will be all right? Those cracks look terrible, and he lost a tooth.”

            “Yes, we will have to patch him up. He’s weak right now, but some rest should put him back on his feet, and of course, we will take good care of him,” Edge said, stroking the side of Sans’ face.

            Fell smiled a little, leaning over to do the same, and then moving so he could press his forehead against Edge’s.

            “Nyeh, heh, heh, I can’t believe we’ve made it,” Fell murmured, his voice slightly giddy. “We’re our own family now!”

            “We are,” Edge said. “Come, let’s clean up the wounds and make him comfortable on the couch, then we can start preparing for our new life.”

            The only thing they had done when they discovered the house was clean the couch and stash blankets and some pillows. This came in handy, as Fell pulled one blanket out to line the couch and placed a pillow down, Edge carefully lay Sans on top of it, and then Fell tucked a light blanket over him to keep him warm and comfortable. They tore a pillowcase into strips and just had to use the soap and water on hand to gently clean the cracks. Nothing could be done about Sans’ tooth until he was awake.

            It only took a couple of hours to tear down the boards, for one to do some food shopping while the other cleaned the kitchen. They both worked together to make a lasagna, moving with practiced ease through the recipe and around one another.

            “Nyeh, heh, remember Sans had us learn to work together in the kitchen because we made such a mess otherwise?” Fell said.

            “Nyeh heh! Oh, we were terrible to each other!” Edge giggled.

            While the lasagna was in the oven, the two braved upstairs. They didn’t go there before due to lack of time, and they both realized that just about anything could be up there waiting for them.

            They stood at the foot of the stairs and looked up. Edge reached for Fell’s hand.

            “Scared, brother?” Fell murmured.

            “Just making sure you don’t run,” Edge replied softly.

            Despite the reassuring squeeze of hands, a cold wave of fear washed over them both.

            “Y-you don’t think, could h-he-?”

            “No. He is done for. Let’s go.”

            Edge took a step ahead of Fell, but they kept their hands tight in one another’s as they went.

            Of course, the two had no cause for caution or concern; the two rooms were fairly empty, though one had an old mattress in the corner. There was a dresser in each room, a bathroom linked the two rooms together, and as they went back downstairs, the twins started planning.

            The lasagna was done and cooling on the counter, and the two checked in on Sans. He hadn’t moved one bit.

            “That’s a little worrisome,” Fell murmured.

            “A little. It has only been a few hours, and he was hurt pretty badly,” Edge said.

            “We should check him.”

            “Good idea.”

SANS  1 ATK  1 DEF  
His HP is critically low.  
He is scared.

            “Cripes,” Fell murmured.

            “Not what I was hoping for,” Edge said, “Rest is good, but he needs healing. Do you think you’re up for it?”

            “For you and Sans, always.”

            Edge smiled and he moved to lift Sans gently, scooting in behind him. Fell went to the other side, lifting Sans’ legs so they lay across his lap. Essentially cradling the smaller monster between them, Edge put one hand over Sans’ sternum, and Fell reached over to put his hand next to his brother’s.

            They closed their eye and concentrated, pouring as much love and intent as they could into their magic. Slowly, their hands glowed green with healing magic and started to seep under Sans’ clothes.

            Everything was still for a few moments, then Sans began to squirm a little under them, as if he were having a nightmare.

            “Nnng, Edge, Fell, please,” he murmured.

            The twins’ eyes snapped open, the green magic fading quickly.

            “We are right here, Sans,” Fell said gently.

            “No, turned, no, maybe, still save,” Sans continued to murmur.

            “Oh, would you wake up, idiot,” Edge mumbled.

            “Edge, be patient!”

            But Sans’ squirms turned into thrashing and the two found themselves trying to hold him down to keep him from hurting them.

            “That’s it,” Edge growled.

            He lifted a hand, and a blue tinge of magic surrounded Sans.

            “Huh, good idea,” Fell said.

            They looked down at their struggling brother and noticed tears were starting to spill from his eye-sockets as they slowly opened halfway, but unseeing.

            “Lost, all is lost,” Sans whispered. “They hate me.”

            Sans’s eyes closed again, his body went limp, and Edge dropped his magic. The twins did another check.

SANS  1 ATK  1 DEF  
His HP is low.  
He is scared and alone; no one wants him.

            “Oh, Sans,” Fell murmured. “That’s not true.”

            Edge was silent, looking down at his older brother, caressing his face briefly before carefully moving off of the couch.

            “Take care of him, I’ll be right back,” Edge said, taking his scarf, which he had set on the arm of the couch with his twin’s and wrapping it around his neck and shoulders.

            “Where are you going?” Fell asked.

            “To do some research.”


	4. Chapter 4

**Summary for the Chapter:**

> Sans wakes up, the twins see the extent of Gaster's damage, and find out something their older brother has been hiding from them.

            Sans slowly opened his eyes, and he was a little surprised to be looking up at a gray ceiling. He was lying on a fairly firm mattress, a thin pillow behind his head, and a clean sheet tucked around him.

            Where was he? Why did his head and mouth feel funny?

            He carefully reached up towards his face, but a voice made him freeze.

            “Finally, lazybones! We were beginning to worry you would dust!”

            “Fell?”

            His younger brother leaned over and pushed his hand back down.

            “I wouldn’t touch those bandages just yet,” Fell said. “Wait here.”

            Fell quickly left the room, though didn’t go far as he heard him call Edge and then he was right back inside.

            Sans began to panic, pushing back and finding himself stuck in a corner.

            “Oh, stars, oh stars, oh stars,” Sans panted.

            “Sans?” Fell tilted his head.

            “W-what happened? Where’s-? I thought I-! You, you both-?!”

            Fell frowned, unsure what to do about his panicking brother, when Edge came into the room, Sans began to shake and continued to mutter in half-sentences.

            “Sans!” Edge exclaimed in a breath of relief, but then worry took over his features. “Sans? Sans, calm down, you’re going to hurt yourself!”

            “Gaster, he, you both, I, he went, the machine!” Sans cried.

            Edge scowled and took a couple of strides forwards and dropped onto the low mattress and gripped Sans’ shoulders firmly.

            “Breath, Sans, you have to breath,” Edge all but ordered. “It is all right, you are safe, I promise you, but I will not say any more until you are calm.”

            “It’s all right, Sans, really,” Fell added.

            Sans’ eyes moved rapidly between the twins, and finally, his breathing slowed and he nodded.

            “Good,” Edge breathed, crossing his arms. “How are you feeling?”

            “Horrible,” Sans murmured. “What happened?”

            “You’ve been unconscious for a week,” Fell said. “You and Father shorted out The Core control panel, or whatever that thing was. He is gone.”

            “Dad- Gaster- is gone?” San stammered.

            The twins each nodded gravely. A small smile quirked the uninjured side of Sans’ mouth up, then he slowly began to laugh.

            “Oh, stars,” he murmured, wiping the tears, wincing as a bit of pain lanced across the one eye. “I, I can’t- wait,” he glanced up and eyed his brothers and realized they each had their own injuries. “Oh, shit, you guys okay?”

            “He’s the one near dusting and he’s asking us if we’re okay,” Edge said with a chuckle, pulling a box out of his pocket as Fell also giggled a little and moved towards the bed.

            “What’s that?” Sans asked, pointing to the box, and letting Fell help him move away from the wall so he could sit.

            “A present of sorts, I guess,” Edge said, opening the box and showing Sans.

            Sans leaned forward and looked at the gold object inside. It had an odd shape, sharp – it looked almost like a fang.

            “You lost one of your teeth in the struggle,” Edge explained, carefully tipping the box so the gold piece rolled into his hand. “I was told how to, well, install it. It’s likely going to hurt, though, and you will need to stay still.”

            Sans couldn’t help tensing when Fell wrapped an arm around his shoulders from behind, the other hand curving in front of his forehead.

            “I’ll hold you, it’ll be okay,” Fell murmured into the side of his skull.

            Sans was somewhat concerned by the pleasant shiver that ghosted up his spine, but it was the only thing that gave him a hint of relaxation before Edge firmly gripped his jaw and started pressing the gold object into his mouth.

            “Hang on, hang on,” Edge murmured when Sans began to squirm, fighting Fell’s increasingly tightening grip and the mounting pain.

            It felt like a sharp, hot poker was being shoved into the top of his mouth. The pain travelled up the crack he now knew trailed from the top of his mouth nearly to his eye. Just when his vision blurred and he felt like he was going to pass out again, Edge backed away and Fell loosened his grip, wrapping both arms around Sans in a gentle hug, rocking him a little.

            “You did it, brother,” Fell murmured.

            “Lucky you have us, especially Fell; if you moved any more it would have injured you further,” Edge said with a slightly exasperated sigh.

            Sans reached up tentatively to touch the new tooth; the area still hurt and badly, but his head still felt like it was in a daze. It hurt too much to try to look at Fell, and instead he sighed and relaxed a little in his brother’s embrace.

            “What else happened?” Sans murmured, his eyes slowly closing. “Where are we?”

            “Snowdin,” Fell said.

            “We scouted a house here ages ago. While our original plans would have had it in better shape, it shall do for now,” Edge explained.

            “Rest for a bit, brother, we will bring dinner up to you,” Fell said, carefully moving himself from behind Sans and helping him to lie down again.

            The smaller skeleton let out a few whimpers of pain, but was dozing by the time his head hit the pillow. Fell smiled down at him, brushing a hand gently over the crown of his skull. Edge sighed and tucked the sheet in around Sans, and the two quietly left the room.

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

            It took another week for Sans to be back to normal; well, as normal as he was going to get. His already low HP took a permanent, critical hit, and it seemed no matter what his brothers did, it was going to stay that way.

            “There is one thing that hasn’t been tried,” Fell said when he and Sans were alone in the house.

            “What’s that?” Sans asked.

            “Putting healing magic directly into your soul.”

            Sans nearly fell off the couch. “Excuse me?”

            “Come on, Sans, don’t be a baby bones,” Fell said, moving towards him. “You know I won’t hurt you.”

            “That’s a bit much, though, don’t you think?” Sans said, scrambling to the other side of the couch.

            “Do you really want to stay at 1HP? One hit away from dusting? You’d leave us with that?” Fell spat angrily.

            Sans cringed; he knew that as tough a front the twins were putting up, they were worried and scared for him. This wasn’t the first time one of them used the possibility of Sans dusting as a guilt trip.

            “Please, let me try, Sans? Or if you’d rather Edge to, that’s okay,” Fell said gently.

            “No, no, it’s okay,” Sans murmured, unable to look his brother in the eye. “Just, uh, be careful yeah?”

            “Of course. Thank you.”

            Sans could only nod mutely, closing his eyes, curling his hands below his sternum as his soul came forth. Fell couldn’t help but wince as he saw the result of their father’s handiwork; cracks and scars marred the surface, one could tell the soul was once a bright and vibrant red, but was now pale, drained of life and energy.

            “Oh, Brother,” Fell whispered, holding his hands out a bit tentatively, understanding fully now why Sans was so hesitant in taking this route.

            Sans said nothing, opening his eyes just enough to watch as he deposited his soul into his brother’s waiting hands, and then he sat back on the couch with a sigh, more from exhaustion than anything, and bracing himself for what was going to come.

            “I’ll be as careful as I can, Sans, nothing bad will happen, but please tell me if, you know,” Fell said.

            Sans gave a weak thumbs-up in response.

            Fell nodded, closed his own eyes, and concentrated on the soul in his hands. Green healing magic began to mist along the surface, Sans made small little sounds from the couch, but Fell ignored them in favor of keeping focused on his task. He pressed a thumb into the center gently, hoping to push the healing energy directly into the core of Sans’ soul.

            Then the unexpected happened.

            Fell couldn’t even gasp as a flood of emotions washed over him, memories of torment, pride, love, loss, dreams of a future that Sans didn’t think he could ever have.

            It was overwhelming, so much information, so much feeling, but above and beyond everything, there was love.

            Then there was darkness.

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

            “What happened?” Fell murmured as he woke.

            “You will have to tell me! I come home to find Sans bent over you trying to wake you up. He said you were trying to put healing magic directly into his soul,” Edge said.

            “Did it work? Is Sans okay?” Fell asked, bolting upright.

            “He’s fine, a little shaken, but fine,” Edge said, putting his hands on Fell’s shoulder and kissing his forehead to calm him before moving to sit in front of him on the bed. Fell crossed his legs to give him room.

            They sat with their foreheads pressed against one another, calming and grounding one another.

            “So what happened?” Edge asked, sitting up straight.

            “I don’t know, exactly,” Fell said. “I was holding Sans’ soul – it looks terrible, by the way – and I, I,” Fell took a deep breath as he tried to find the words. “I think I was inside of Sans, in a way. I saw a lot of his memories, and I could feel what he was feeling, physically and emotionally.”

            Edge blinked. “Are you sure?”

            Fell nodded. “There’s a lot more, Brother.”

            “Oh?”

            “Sans loves us.”

            “Well we knew that!”

            “No, Edge, I mean he loves us like how you and I love him, how we love each other? Like how we love each other as more than brothers?!”

            Fell would have laughed at Edge’s face as the wheels in his head turned over this new piece of information, but he was too excited as the true weight of his own words were also hitting him.

            “Edge! He loves us both!” Fell exclaimed, launching himself forward to kiss Edge, toppling him backwards with a giggle as their mouths met.

            Edge kissed him back a little, but mostly was in too much shock to respond much.

            Fell pulled away. “Are you all right?”

            “Yes, yes,” Edge said, taking a deep breath and letting it out slowly. “I’m happy, I really am, just… if that is the case, why has he not said anything?”

            “Oh, that’s true,” Fell said. “I’m sure he is just frightened.”

            Edge sighed, rubbing his face. “I’m certain he is. He didn’t say much to me, so I do not know if he knows that it’s even possible to view one’s memories and feelings through their soul. I’m concerned that Sans may feel embarrassed or would be confused, or worse, just plan not believe us if we told him.”

            “He’s our elder! Shouldn’t he know how to handle it?” Fell crossed his arms and huffed.

            “Perhaps, but if he’s done nothing but spend his life being experimented on, then he wouldn’t have had the exposure we had and be as cool as we are. We don’t know what he can handle anymore. What if the shock dusts him?”

            “Okay, fine,” Fell sighed in frustration. “Then what do we do?”

            “Nyeh, heh, heh, actually, this will work out quite perfectly.”

            Fell raised a brow bone in skepticism, but then he relaxed into a look of curiosity when Edge pulled out a flat box from his inventory.

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

            Sans blinked down at the object on the table.

            “Ya gotta be kiddin’ me,” he murmured.

            “No, Sans, we are quite serious,” Edge said.

            “It’s necessary for our survival; we have been observing this town for weeks and learned what is acceptable out here. Life here isn’t like how it is in the capital,” Fell explained.

            “But, a collar? Really?”

            “Yes. It marks you as ours. Well, officially, as Property of The Great Papyrus, Future Member of the Royal Guard,” Edge said with a smug smile.

            Sans’ head dropped to one side. “Huh?”

            “You see, after we fled the Capital, Dr. Alphys was left in charge. No one really knows what’s become of us. Also, with the exception of Dr. Alphys, no one outside of our family knows that we are twins,” Fell said.

            “We will use this to our advantage; I have met and spoken with the current head of the Royal Guard, a monster named Undyne. She has been training us for the Royal Guard, though we are not there quite yet. In the meantime, you have a job as a sentry, watching for humans. I, or Fell, will patrol the town and the woods,” Edge said.

            “Hey, that’s not fair, one of you gets to stay home?” Sans argued.

            “Whoever stays home that day will be responsible for the upkeep of this house, cooking, cleaning, and training; it’s not as easy as it sounds,” Fell said.

            “Besides, being a sentry isn’t difficult, even a lazy-bones like you can do it,” Edge said, standing up and walking to stand by Sans.

            “And it’s the best way to keep an eye on you, what with your HP and all,” Fell said, moving to stand on Sans’ other side.

            Sans felt his head spinning; everything the twins said made sense, it was all logical, it all made sense. He stared at the red, leather collar, studded with small gold spikes, and a small charm with ‘Papyrus’ etched into it. It occurred to him that a lot of thought went into all of this, even the collar. The prospect of wearing it, being marked as the twin’s property, an official show that they were going to take care of him, it all stirred something deep in his soul. He always loved them, but he knew it really couldn’t ever be. They had so much potential, they could have any monster in the Underground, he wasn’t worthy of either of them.

            “Shall we put it on, see how it fits?” Edge asked.

            Sans glanced up, realizing the twins were on either side of him, and he felt a shiver run up his spine.

            It was a lot more pleasant than he was willing to admit.

            Edge picked the collar up from the box, Fell put a hand on Sans’ shoulder, their hands gently coaxed his chin up the leather pressing against the front of his neck, then he naturally tilted his head forward and shivered again as he felt their slender fingers buckle it into place.

            “It looks good on you, brother,” Edge murmured into the side of his skull.

            “We will always keep you safe,” Fell whispered, tucking a finger under the collar and tugging very gently.

            Sans prayed neither would notice the bulge forming in his pants.


	5. Chapter 5

**Summary for the Chapter:**

> The boys adjust to their new life, confessions are made, feelings are revealed, but are they mutual?

            Over the next few weeks, Sans and the twins settled into their new life and routine, the three of them thrilled to be living their own lives. Sans was a little nervous, though; expecting someone to recognize them, figure things out, and report them to King Asgore. What would even happen if he found out? Would he even care? Then there were the nightmares; dark, twisted visions of Gaster, him not really being gone and coming back to get his revenge against his traitorous sons.

            The twins did their best to reassure their brother, often taking harsh stances against him out in public to keep up a tough image, but at home, there were gentle murmurs, hugs, and affection.

            The twins were also being more affectionate than what would be deemed necessary, since now they knew how Sans felt about them, they decided to try to hint to him that they felt the same. Fell noticed he got a small blush from Sans anytime he tugged on his collar when they reminded him of the promise the accessory meant. Edge started brushing his hand down Sans’ spine when he noticed a small response in the form of a small, pleasant sigh from the shorter skeleton.

            When Sans calmed a little more, they started dropping kisses on the top of his skull as they placed his meals in front of him, squeezing his shoulder in a more intimate manner when they left him at his sentry station, and being more openly affectionate with each other in front of him, and he was very much noticing and finding himself getting turned on by it. Sans didn’t know what the two of them were up to, but it was driving him crazy.

            Little did he know that it was driving the two of them crazy as well.

            “Brother, I want to confess to him,” Edge said as they got into bed one evening. “It’s making me mad; it’s one thing that we have to control ourselves out there, but in our own sanctuary?! It’s almost insulting!”

            “Shh,” Fell murmured, turning off the light and slipping under the covers Edge held for him. “I know, but remember we wanted to make sure Sans was settled from his ordeal before we dropped this on him.”

            “Well, yes, but,” Edge grumbled as the two settled comfortably against each other, Fell leaning his head on Edge’s shoulder as Edge tucked them in and wrapped an arm around him. “I’m just getting impatient.”

            “Mmm, and rightfully so, I understand, Edge, you know I do.”

            The two shared a matching smile, gently kissed each other, and settled more into their bed for sleep when a sound caught up their attentions.

            It was a little difficult to hear but after exchanging wordless, questioning glances, the twins realized that the panting groans was coming from the room next door.

            “Is he okay?”

            “Maybe it’s another nightmare?”

            “We should check on him.”

            Before they could move, they heard Sans moaning their names, the panting slowed, then stopped altogether.

            “Was, was he-?”

            “I, I think so.”

            Another few beats of silence.

            “We confess tomorrow.”

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

            “SANS! GET UP AND GET DOWN HERE BEFORE BREAKFAST GETS COLD!” Fell ordered from outside the bedroom door.

            “Yeah, yeah, ‘m comin’,” Sans muttered, kicking off the sheet his legs had become tangled in during the night.

            Another restless night; at first, he couldn’t sleep, and he even tried masturbating to try to squeeze out the last bit of nervous energy that was keeping him awake, and he grimaced when his foot gazed a damp spot in his sheet. He glowered at the muted red spot of magic and wondered how he was going to hide it from the twins. Then he sighed, momentarily ashamed of the thoughts that had caused that spot to be there.

            He really needed to get laid or get over his own brothers.

            Sans was downstairs a moment later, and everything seemed to be normal, but Sans senses an odd energy in the air, something... tense.

            “You guys okay?” Sans asked as he sat.

            “Of course we are, brother,” Fell said, stirring the eggs on the stove.

            “Why do you ask, Sans?” Edge asked from the other side of the table.

            “Eh, just, y’know, checking,” Sans said with a shrug.

            They were silent as Fell finished their breakfast and served the eggs on the three plates. Sans swung his legs under the table, staring into space, letting puns run through his mind and a slow grin spreading across his face at the thought of busting them out and starting the day with annoying his adorable brothers.

            But then he was distracted by something running along his leg, it started just below his knee and trailed down to his ankle. It felt like bone, and he glanced under the table briefly and found a bony foot making its way back up his tibia. He knew it belonged to Edge and he glanced back up at his brother. Edge was pouring over a junior jumble, his face indicating that, as per usual, he was having a hard time solving it. His foot never stopped languidly caressing his leg and Sans’ mind was scrambling for a reaction as his toes began brushing higher, passing lightly over an old wound just beneath his patella when he was distracted by a plate being set in front of him and Fell’s hand on his shoulder.

            “Eat, brother,” Fell murmured, pressed a kiss to the side of Sans’ skull, lingering a little longer than usual as Edge’s foot retreated. “Sans? Are you all right?”

            “Eh, heh, sorry, bro, I w-was trying to c-cr-crack a pun,” Sans said somewhat weakly.

            Fell scowled, sweeping behind Sans, hooking a finger under the back of his collar and tugging firmly. Sans choked on his gasp and fought to keep the moan of pleasure that threatened to spill out behind his teeth; no matter how many times he had his collar pulled in love and frustration, it always sent hot magic straight to his pelvis, and it was halfway there when Edge was touching him.

            “Hmph. They’re not always as eggs-cellent as you think, Sans, Nyeh, heh, heh,” Fell murmured.

            Sans flushed completely red; what was going on? Why were his brothers being so... intimate?

            _No, no, it’s all in your head, just your imagination,_ Sans thought. Though he was second guessing himself when Fell went to serve Edge his breakfast and he pressed a quick kiss to the others cheekbone as he bent down. The two shared a look before Fell went to grab his own breakfast plate, and Sans was glancing quickly between the two as they began to eat.

            After a few beats, since nothing else odd seemed to happen, Sans took up his fork to begin his breakfast. When he got the first bite into his mouth, he froze when he felt bone sliding against him again. He swallowed hard as Fell’s hand reached over and rested over his own. Sans waited for a few beats, Edge’s foot was nearly pressed against his pelvis when he dropped his fork, his face burning red.

            “Sans?” Edge asked.

            “What are you two doing?!” Sans asked, his voice stuttering.

            “Just making contact,” Fell said with a slow smile. “It’s good for monsters to have physical contact.”

            Sans opened his mouth - to say what he wasn’t sure - but it didn’t seem to matter as Edge’s foot pressed against the side of his pelvis, Fell’s fingers trailed lightly along the back of his hand.

            “And we would like to have more physical contact with you, Sans,” Edge murmured, looking at him intensely, word puzzle forgotten.

            Sans went back to his eyes darting between them.

            “You two, uhm,” he stammered, unsure whether to ask if they lost their minds or if he was losing his own.

            “We have discussed this for a very long time,” Edge said.

            “We have cared for each other in a greater capacity than brothers for quite a while as well,” Fell added. “And we feel the same for you.”

            Sans was speechless.

            “This is a lot to take in, not surprising, as it must be a lot knowing that two really cool skeletons adore you so,” Edge said, his foot leaving Sans’ pelvis so he could stand, walking to Sans’ other side. Edge caressed his cheekbone before curving his hand under his jaw. “You do not have to give us an answer now, Sans, and please do not feel any obligation one way or the other. We love you, and would like to date with you.”

            “We would,” Fell confirmed. “Think it over. For now, finish eating, otherwise we will all be late.”

            The taller skeletons each dropped a kiss on the top of Sans’ skull before moving on to either chores or to prepare for sentry patrol, leaving the elder brother sitting stunned by himself.

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

            The day was a nervous and long one for all three of them; Fell and Edge texted more than usual, Edge considered cutting his patrol short, Fell wondered if he should make something special for dinner regardless of Sans’ answer, Sans sat silently at his post and mostly stared at the surface of the worn wood that he usually sprawled over and napped on. Even when Monster Kid tried to raise hell for him, it was mostly ignored.

            Sans’ main problem was that he wasn’t sure if Edge and Fell were sure of what they were doing. But, sure they did, they were adults, albeit very young adults, and yes they were sheltered but they were not stupid. They were the ones who had crafted their escape, after all, so Sans had to give them a lot of credit.

            But did they love him? Or did they pity him and just wanted to take care of him?

            _Nah, that’s stupid and you know it,_ the voice of inner truth said. _They’re already taking care of you, got you a collar and everything to protect you, they just want to take the nest step._

            The next step.

            Sans began to sweat at the thought; he already harbored a lot of guilt for thinking of them in such a manner, but apparently, they were thinking of him in the same way, so was it really something to be guilty about? Yeah they were both cool, and very good-looking monsters, but more than that, they did have a kindness that wasn’t often found in their world, part of them stayed kind despite their treatment. Perhaps it was due to his own intervention, or due to them just being that cool. Anyone should consider themselves lucky to be the partner of either one of them, and they both wanted him.

            He would be stupid to reject them.

            “SANS!”

            He jumped at the bark of his name and looked up to find Edge standing with his arms crossed.

            “’sup, bro?” Sans asked as casually as he could.

            “THE DAY IS OVER. HONESTLY, ARE YOU SO LAZY THAT YOU CANNOT KEEP TRACK OF TIME?” Edge demanded.

            It was all part of the act on the outside, and Sans could see in Edge’s eyes that today, it kind of hurt to be so harsh.

            “Guess it just slipped away from me,” Sans said in a very weak attempt at some sort of joke or pun.

            “BE THAT AS IT MAY,” Edge started, then he sighed. “Let’s go home.”

            The walk home was silent and Sans knew that he had to make a decision by the time they reached the house. Or, rather, he should make a decision, as he knew the twins must have been as nervous as he was about all of this, maybe even moreso.

            But his mind was definitely made up.

            They reached the house, Edge opening the door and letting Sans enter first, shutting the door and locking it behind him.

            “Welcome home,” Fell called from the kitchen when the last lock clicked into place.

            Fell came out of the kitchen, smiling at his brothers, and then looking nervously at Sans. Sans glanced over and saw Edge was standing there, a bit nervous as well. He sighed and shoved his hands into his jacket pockets.

            “Uhm, you guys know that this isn’t normal, yeah?” Sans asked.

            The two were silent, though gave small motions of acceptance.

            “We could probably never show any affection out in the open until we knew someone could be trusted, and that could be really strenuous.”

            They again gave small nods as their faces began to show disappointment.

            “Are you guys sure you wanna go through that?”

            “We’ve been hiding for years,” Edge murmured.

            “Don’t see any reason to change that particular aspect now,” Fell said, taking a deep breath and straightening. “We still love you, Sans, we understand you decision, and we thank you for your honesty.”

            Sans tilted his head as the looks of disappointment on the twin faces grew.

            “Then why do you guys look so upset?”

            “Yes, we still love you and always will, but facing rejection is never a happy thing,” Edge muttered.

            “Rejection? Did I say I didn’t want this?”

            The two started themselves and looked at Sans, who was grinning at them.

            “You took it all wrong, you dorks,” Sans chuckled. “I was just trying to say, if you two are certain, I would love to be your boyfriend.”

            Sans wasn’t exactly sure how he ended up sandwiched between the twins on the couch as they rained kisses down on him, but he didn’t mind. Fell gripped his collar and pulled him close and kissed him deeply, and before he could get over being dazed from that, Edge also tugged on the collar and took his turn.

            “You two keep doin’ that, and you’ll wreck me without taking my clothes off,” Sans nearly slurred, his head spinning.

            “Mm, we can work on that,” Edge said, slipping Sans’ jacket off his shoulders.

            “Perhaps more exposure to love will get you used to it,” Fell said, running his hands over the worn t-shirt over Sans’ ribs.

            “Mmm… dunno if I could ever get used to that, but, that might not be such a bad thing after all,” Sans panted

            “Nyeh, heh, heh, don’t you worry Sans,” Fell murmured, moving up as Edge bent down so they both could murmur on either side of his skull, their deep voices vibrating pleasantly in his head.

            “We’ll take good care of you.”


End file.
